The invention relates to a work spindle or operating spindle for a machine tool comprising a rotatably mounted spindle guard tube, which is drivable by a motor, a clamping arrangement disposed at an end of the spindle guard tube, a clamping force generator, which is arranged on the spindle guard tube and operates the clamping arrangement, and which has at least one first cylinder chamber enclosed by a first cylinder housing and a first piston, which in order to generate a clamping force in the clamping arrangement, is subjected to a pressurized medium, and a connection between the clamping force generator and the clamping arrangement.
Such work spindles are known from the prior art. The problem with such work spindles is that different clamping forces are necessary, depending upon the clamping task in the clamping arrangement.
Although it is possible, in principle, to vary the clamping forces by varying the pressure of the pressurized medium for generation of the clamping force, this pressure variation is subject to technical limits.
For this reason, the clamping force generator has often been replaced in its entirety in order to generate different clamping forces. However, such a replacement of a clamping force generator arranged on a work spindle is the equivalent of refitting the machine, since a plurality of peripheral components must be disassembled and re-assembled. This refit is particularly costly in the case of machine tools with several work spindles.
In the sense of the invention, the term work spindles may refer to spindles, wherein work pieces are to be clamped in their clamping arrangement, but it is also possible to use these spindles as tool spindles.
In particular when using tool spindles, it is frequently a requirement to clamp completely different work pieces in the case of flexible use of the machine tool. The range of work pieces extends from solid steel parts, in the case of which a high clamping force is also necessary because of the high machining forces, to thin-walled aluminium parts, in the case of which minimal clamping forces must be used--in order to prevent deformation.